The United Automobile Workers union unexpectedly announced on Monday that it was dropping its effort to have a new unionization vote ordered at the Volkswagen plant in Chattanooga, Tenn.

The union lost a vote at the plant in February, 712 to 626, and soon afterward it asked the National Labor Relations Board to order a new election, asserting that anti-union statements and threats by Tennessee lawmakers had prevented a fair election.

Bob King, the U.A.W.’s president, said his union was withdrawing its appeal based on the belief that the labor board’s adjudication process “could drag on for months or even years.”

The vote was a major defeat for the U.A.W. because Volkswagen, unlike most American companies faced with unionization drives, did not even oppose the effort. If the union had won the vote, the plant would have become the first foreign-owned auto factory in the South to be unionized, and many said it could pave the way to unionizing the Daimler-Benz plant in Vance, Ala., and the BMW plant in Spartanburg, S.C.

The U.A.W. dropped its appeal on the same day that the N.L.R.B.’s Atlanta regional director was scheduled to begin a hearing in Chattanooga to take evidence on whether the lawmakers had prevented a fair unionization vote.

The Republican lawmakers whom the U.A.W. blamed for its loss said the union’s effort to overturn the election was a case of sour grapes and a refusal by the union to own up to its failure to win majority support at the three-year-old plant.

U.A.W. officials said on Monday that they still hoped to unionize the VW plant some day. Kenneth Dau-Schmidt, a labor law professor at Indiana University, said that withdrawing the case meant that a new unionization vote could be held there sooner than if the U.A.W. pursued its appeal through the labor board.

Under federal labor law, the union can hold a new unionization vote at VW next February. In contrast, if a labor board process included federal court appeals, it could have taken two years for an N.L.R.B. decision ordering a new election to take effect.

Photo

Bob King, the U.A.W. president, said the union was ready to look to the future.Credit
Erik Schelzig/Associated Press

“This way they can just file for a new election next February,” Professor Dau-Schmidt said, noting that the union would be spared legal expenses and avoid having anti-U.A.W. groups seek to sully it during the N.L.R.B. process.

The U.A.W. asserted that Gov. Bill Haslam had poisoned the atmosphere for a fair election by threatening to withhold additional subsidies to the assembly plant if the workers voted to unionize. In addition, the union asserted that Senator Bob Corker had improperly sought to influence the election by saying that VW officials had told him that they would bring a second production line to the plant if the workers voted against unionizing. Both Mr. Haslam and Mr. Corker are Republicans.

Mr. Haslam’s office said he did not make any improper threats against the U.A.W., and Mr. Corker has repeatedly maintained that all he was saying was the truth.

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In a news release, Mr. King said, “The U.A.W. is ready to put February’s tainted election in the rearview mirror and instead focus on advocating for new jobs and economic investment in Chattanooga.”

Gary Casteel, the union’s director for the South, said on Monday that the U.A.W.’s priority was to press Volkswagen to create more jobs in Tennessee by adding a new line at the Chattanooga plant for sport utility vehicles.

If the Chattanooga plant wins the new production line this year, and the U.A.W. seeks a new election next year, Tennessee officials could not again threaten to prevent that vital line from coming — a line that many workers saw as vital to assuring the plant’s long-term future.

In a statement, Mr. Corker said the U.A.W.’s decision to drop the appeal showed that its objection “was nothing more than a sideshow to draw attention away from their stinging loss in Chattanooga.”

Leaked documents showed that Mr. Haslam’s administration offered nearly $300 million in incentives to bring the new S.U.V. line to Chattanooga, but said that money would be contingent on the plant’s remaining nonunion.

Some Volkswagen officials seemed quietly to back unionization because it would have helped them set up a German-style work council, a group of white-collar and blue-collar workers that helps shape a plant’s policies.

A version of this article appears in print on April 22, 2014, on Page B3 of the New York edition with the headline: U.A.W. Drops Appeal of VW Vote in Tennessee. Order Reprints|Today's Paper|Subscribe